Removing multiple newlines from EOF?

Hello,

When using `terraform fmt` I noticed that multiple newlines are not removed (_ie_ collapsed down to a single newline) from ends of files. Would maintainers be open to a PR that would fix this?

Thanks!

Start by reproducing the behavior through the `terraform fmt` formatting path and locate the formatter code that handles end-of-file newlines. Add coverage for files ending with multiple newlines; done means formatting collapses them to a single trailing newline without changing other content.

Written by the indexing model from the issue text.